In today's information age, the typical person is deluged with information from multiple media sources, and rarely has time to focus exclusively on any one source of information. It is therefore common for individuals to, for example, read a newspaper while listening to a radio program as background music at the same time. In such a case, the reader will typically only focus on the radio program when it is of special interest to him or her.
Likewise, many individuals like to listen to radio news broadcasts only for certain segments of the program, for example, the weather forecast or a particular stock price. If the listener also desires to listen to some other program before and after the segment of interest, he or she typically has to change the tuning of the radio before or after the desired news segment. Also, for example, if the listener is not aware of the precise time when the news segment of interest is to be broadcasted, he or she may miss it entirely, i.e., it may be broadcasted before the tuning is changed.
Apparatus for providing multiple audio channels from which a single listener may select one program is known, for example, from U.S. Pat. No. 3,876,953 to Abel, which describes, in a classroom setting, apparatus enabling a student to select an audio program appropriate for their skill level.
U.S. Pat. No. 4,660,192 to Pomatto describes a simultaneous AM and FM transmitter/receiver that allows simultaneous broadcasting on both AM and FM channels with the same RF carrier, thereby providing two separate channels of information (one AM and one FM). Like the Abel patent, however, the Pomatto apparatus provides for selection and amplification of only one of the channels at any one time.
U.S. Pat. No. 4,190,803 to Imamura describes a multifrequency receiver that alternately provides either a priority channel or a nonpriority channel. The Imamura apparatus includes a switching system that inhibits broadcast of the nonpriority channel when the priority channel is operative. Like the devices described in the foregoing patents, Imamura provides only one channel of programming at any one time.
In view of the desirability of broadcasting dual audio programs simultaneously to a single listener, and the absence of such features in previously known audio apparatus, it would therefore be desirable to provide audio apparatus that would allow tuning to two different audio channels so that the two programs could be broadcast simultaneously to a listener.
It would further be desirable to provide dual audio program apparatus having volume control circuitry that allows a first, foreground, audio program to be played at a higher volume and a second, background, audio program to be played at a lower volume.
It would be still further desirable to provide dual audio program apparatus that enables the content of a foreground audio program and of a background audio program to be selected according to a listeners' preferences.
It would be yet further desirable to provide dual audio program apparatus that enables a foreground program and a background program to be selectively interchanged, either instantaneously or in a gradual and continuous manner.
It would be even further desirable to provide dual audio program apparatus that enabled either or both of the audio programs to be selectively muted.